Sigmoid colon mucosa-associated lymphoid tissue lymphoma complicated with hepatitis B virus infection: a case report

Mucosa-associated lymphoid tissue (MALT) lymphoma is a low-grade malignant extranodal marginal zone B-cell non-Hodgkin lymphoma, which most commonly originates in the stomach. Primary colorectal MALT lymphoma is rare clinically, and there are currently no unified diagnostic and therapeutic criteria. Besides, the association between chronic hepatitis B virus (HBV) infection and sigmoid colon MALT lymphoma remains unclear. Herein, we report a 69-year-old male patient with primary sigmoid colon MALT lymphoma complicated with HBV infection. The patient was admitted due to a colorectal mass detected during physical examination, without typical gastrointestinal symptoms. Primary sigmoid colon MALT lymphoma was confirmed by colonoscopic biopsy, immunohistochemistry, gene rearrangement analysis and PET-CT. The patient did not receive targeted anti-tumor therapy, and instead received basic management including anti-HBV treatment combined with regular follow-up. After two years of standardized follow-up, the primary lesion in the sigmoid colon resolved, with no disease progression or recurrence. This case suggests that for asymptomatic localized primary sigmoid colon MALT lymphoma, the management strategy of targeted therapy for chronic infection such as HBV infection combined with intensive monitoring and regular follow-up merits further discussion.